136 lines
3.9 KiB
C
136 lines
3.9 KiB
C
/*
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* Brickworks
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*
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* Copyright (C) 2022 Orastron Srl unipersonale
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*
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* Brickworks is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3 of the License.
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*
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* Brickworks is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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*
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* File author: Stefano D'Angelo
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*/
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/*!
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* module_type {{{ dsp }}}
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* version {{{ 0.2.0 }}}
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* requires {{{ bw_config bw_common }}}
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* description {{{
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* Pinking filter.
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*
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* ...
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* }}}
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* changelog {{{
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* <ul>
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* <li>Version <strong>0.2.0</strong>:
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* <ul>
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* <li>Refactored API.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.1.0</strong>:
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* <ul>
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* <li>First release.</li>
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* </ul>
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* </li>
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* </ul>
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* }}}
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*/
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#ifndef _BW_PINK_FILT_H
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#define _BW_PINK_FILT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <bw_common.h>
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typedef struct _bw_pink_filt_coeffs bw_pink_filt_coeffs;
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/*! api {{{
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* #### bw_pink_filt_state
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* ```>>> */
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typedef struct _bw_pink_filt_state bw_pink_filt_state;
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/*! <<<```
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* State
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* >>> */
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static inline void bw_pink_filt_set_sample_rate(bw_pink_filt_coeffs *BW_RESTRICT coeffs, float sample_rate);
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/*! ...
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* #### bw_pink_filt_reset()
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* ```>>> */
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static inline void bw_pink_filt_reset_state(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state);
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/*! <<<```
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* Resets the given `instance` to its initial state.
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* >>> */
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static inline float bw_pink_filt_process1(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, float x);
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/*! ...
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* #### bw_pink_filt_process()
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* ```>>> */
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static inline void bw_pink_filt_process(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, const float *x, float* y, int n_samples);
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/*! <<<```
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* Lets the given `instance` process `n_samples` samples from the input
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* buffer `x` and fills the corresponding `n_samples` samples in the output
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* buffer `y`.
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* }}} */
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/*** Implementation ***/
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/* WARNING: This part of the file is not part of the public API. Its content may
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* change at any time in future versions. Please, do not use it directly. */
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struct _bw_pink_filt_coeffs {
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// Coefficients
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float k;
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};
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struct _bw_pink_filt_state {
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float s1_z1;
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float s2_z1;
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float s3_z1;
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float s4_z1;
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};
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static inline void bw_pink_filt_set_sample_rate(bw_pink_filt_coeffs *BW_RESTRICT coeffs, float sample_rate) {
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coeffs->k = bw_sqrtf_2(44100.f / sample_rate);
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}
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static inline void bw_pink_filt_reset_state(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state) {
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state->s1_z1 = 0.f;
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state->s2_z1 = 0.f;
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state->s3_z1 = 0.f;
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state->s4_z1 = 0.f;
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}
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static inline float bw_pink_filt_process1(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, float x) {
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const float s1 = 0.320696754235142f * x + state->s1_z1;
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state->s1_z1 = 0.999760145116749f * s1 - 0.3204568993518913f * x;
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const float s2 = 0.2870206617007935f * s1 + state->s2_z1;
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state->s2_z1 = 0.9974135207366259f * s2 - 0.2844341824374191f * s1;
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const float s3 = 0.2962862885898576f * s2 + state->s3_z1;
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state->s3_z1 = 0.9687905029568185f * s3 - 0.265076791546676f * s2;
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const float s4 = 0.3882183163519794f * s3 + state->s4_z1;
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state->s4_z1 = 0.6573784623288251f * s4 - 0.04559677868080467 * s3;
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return coeffs->k * s4;
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}
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static inline void bw_pink_filt_process(const bw_pink_filt_coeffs *BW_RESTRICT coeffs, bw_pink_filt_state *BW_RESTRICT state, const float *x, float* y, int n_samples) {
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for (int i = 0; i < n_samples; i++)
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y[i] = bw_pink_filt_process1(coeffs, state, x[i]);
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}
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#ifdef __cplusplus
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}
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#endif
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#endif
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